The present invention relates to a sputtering apparatus for forming a thin layer by utilizing the magnetron sputtering method.
In Japanese Patent Application No. 11-228377, the present applicant has proposed a technology for obtaining plasma having a high density in the surrounding of a substrate to be sputtered by disposing auxiliary magnet poles in the vicinity of magnetron type sputtering evaporation sources in order to confine with a high efficiency the plasma generated from the evaporation sources in the surrounding of a solid substance to be deposited, i.e., a substrate.
In a technology proposed by Japanese Patent Application No. 11-228377, for instance, magnetron type sputtering evaporation sources and auxiliary magnet poles are arranged in such a manner that they surround a solid substance to be deposited, in which case, the polarity of the auxiliary magnet poles is aligned so as to be opposite to the polarity of the outside magnet poles forming the magnetron for an evaporation source, so that the magnetic field is formed such that it surrounds the substrate so as to confine the plasma into the surrounding of the substrate.
In another technology proposed by Japanese Patent Application No. 11-228377, for instance, magnetron type sputtering evaporation sources and auxiliary magnet poles are arranged so as to surround a solid substance to be deposited, in which case the polarity of the auxiliary magnet poles is aligned in the same direction as the polarity of the outer magnet poles forming the magnetron for an evaporation source, so that the magnetic field is concentrated between the adjacent evaporation sources and the auxiliary poles, thereby enabling a plasma generated from the evaporation sources to be confined within the surrounding of the substrate by the mirror effect.
It is a basic object of the present invention to alter with ease the shape of the magnetic field, when the auxiliary magnet poles are mounted in a sputtering apparatus.
In other words, an alteration of the shape of the magnetic field in the vicinity of the substrate makes it possible to adjust the density of the plasma in the vicinity of the substrate and, at the same time, to control the substrate bias current.
In this case, the alteration of the shape of the magnetic field can be realized, for instance, by supplying an electric current to coils disposed on the rear surface of the evaporation sources. However, since the coils are apart to some extent from the discharge space, the effect of alteration is relatively small and besides there appears a possible danger of disturbing the magnetic field above the evaporation sources.
In such a sputtering apparatus as that in Japanese Patent application No. 11-228377, wherein auxiliary magnet poles are disposed, the shape of the magnetic field can be altered by remounting the auxiliary magnet poles to alter the polarity thereof in the direction to the substrate, after the auxiliary magnet poles are dismounted. However, this causes a great deal of work to be put for dismounting/mounting the auxiliary magnet poles, thereby causing a less workability to be provided. Moreover, the dismounting/mounting of the auxiliary magnet poles provides setting only an S or N polarity in the direction towards the substrate and therefore only two types of the shape of the magnetic field are formed in the vicinity of the substrate, so that the shape of the magnetic field cannot be precisely altered.
In the case of altering the shape of the magnetic field by dismounting/mounting of the auxiliary magnet poles, the shape of the magnetic field cannot be altered during the process of deposition.
In the present invention, the auxiliary magnet poles are used to alter the shape of the magnetic field, and for this purpose the following techniques are employed: In accordance with a specific aspect of the invention, a sputtering apparatus wherein one or more magnetron type sputtering evaporation sources and one or more auxiliary magnet poles are arranged so as to enclose a solid substance to be deposited, wherein an angle changing mechanism is provided to change the alignment angle of said one or more auxiliary magnet pole relative to the solid substance to be deposited in order to alter the shape of the magnetic field which is produced by the magnetron type sputtering evaporation sources and the auxiliary magnet poles.
The alteration of the alignment angle of the auxiliary magnet pole relative to the solid substance to be deposited by means of the changing mechanism for the auxiliary magnet poles allows the shape of the magnetic field to be intentionally altered, so that the density of plasma can be altered to a greater extent in the vicinity of the solid substance to be deposited (substrate). Furthermore, the adjustability of the substrate bias current permits the conditions of forming the layer at an optimal bias current to be selected in accordance with the type of the layer and the type of the substrate.
In accordance with the invention, the usage of coils is not required to alter the shape of the magnetic field, thereby enabling the cost of preparing the coils, a power supply for the coils and the like to be saved and, at the same time, allowing the disturbance in the magnetic field in the evaporation source to be excluded. Since, moreover, the system according to the invention provides an easier alteration of the shape of the magnetic field in a greater amount, compared with the coil system, the bias current can be adjusted in a wide range.
In accordance with the invention, it is preferable that the angle changing mechanism is capable of changing the alignment angle of the auxiliary magnet poles at an arbitrary value. In this case, the changeability of the auxiliary magnet poles in an arbitrary angle permits the shape of the magnetic field to be finely altered, so that the bias current can also be finely adjusted.
In accordance with the invention, it is preferable that the shape of the magnetic field can be altered easily even during the deposition process, if the angle changing mechanism can be driven during the deposition process. In particular, it is preferable that if the mechanical power supply used for changing the angle of the auxiliary magnet poles for the angle changing mechanism is disposed outside the chamber, a simple structure can be provided.
In this case, a manual manipulation unit disposed outside the chamber to manually operate the angle changing mechanism outside the chamber can be employed as a mechanical power supply. Alternately, a driving apparatus (for example, a motor or a pneumatic device) for automatically changing the alignment angle of the auxiliary magnet poles by supplying a mechanical power to the direction changing mechanism from the outside can also be used as a mechanical power supply.
Moreover, when a plurality of auxiliary magnet poles is disposed, it is preferable that the alignment angle can be simultaneously changed for these auxiliary magnet poles. Such synchronization in the alignment of the auxiliary magnet poles allows the shape of the magnetic field to be totally altered.